In chain surveying, the area to be surveyed is divided into a number of shall well conditioned triangles. In this regard, which of the following conditions should satisfy for the triangle to be well conditioned?
1
No angle is less than 50° or greater than 100°
2
An angle is less than 20° or greater than 130°
3
An angle is less than 30° or greater than 120°
4
No angle is less than 30° or greater than 120°